Current automotive engine fuel injection systems employ electromagnetic injectors to meter and deliver the fuel to the engine. Throttle body fuel injection systems employ one or two injectors that deliver the fuel into the air flowing through the engine throttle body, and the mixture of air and fuel then flows through the engine inlet manifold to the inlet ports of the engine combustion chambers. Port fuel injection systems, on the other hand, typically employ individual injectors to deliver fuel directly to each of the inlet ports.
A throttle body fuel injection system with only one or two injectors has a cost advantage over a port fuel injection system with its several injectors and the associated fuel rails. However, port fuel injection systems offer advantages in engine operation. Those comparative advantages present incentive for a fuel injection system in which a single injector meters fuel and a plurality of nozzles deliver the fuel to the engine inlet ports.